Gliederung

Objective: It has been shown that patients with unilateral pure tone tinnitus may benefit from electrode implantation and permanent electrical stimulation of the auditory cortex. Until now, the implantation site has been determined according to the results of neuronavigated transcranial magnetic stimulation (TMS) and of functional magnetic resonance imaging (fMRI). This is the first report of a patient in whom the implantation was guided by a region of hyperactivity in a positron emission tomography (PET) scan.

Methods: 45-year-old patient with a high pitched tinnitus, predominant on the right side. Extensive conservative therapy did not improve the tinnitus. TMS over the left motor/auditory cortex could reduce the loudness of the tinnitus tone temporarily. A FDG-PET scan revealed a region of hyperactivity in the primary and secondary auditory cortex in the left hemisphere. The PET scan was fused to a T1-weighted MRI sequence (MPRage, 1.5 mm slice thickness) and prepared for intraoperative neuronavigation. We implanted an epidural electrode with 16 contacts over the left auditory cortex overlying the hyperactive region in the PET scan. The electrode was connected to an extension and a neurostimulator which was implanted abdominally. Surgery was followed by extensive clinical testing of different stimulation parameters. Written informed consent from the patient and a positive vote from the local ethical committee were obtained prior to surgery.

Results: No complications due to craniotomy, electrode, and neurostimulator implantation or epidural stimulation occurred. The loudness of the right sided tinnitus tone was reduced only mildly and temporarily under certain stimulation parameters. These effects were not reproducible after exhaustion of the initial benefit.

Conclusions: Epidural cortical stimulation does not reduce the loudness of the tinnitus tone in all patients, who respond to TMS. The value of PET guidance for the location of the implantation site has to be determined in further studies.